changed the directory structure for libraries
Revert "changed the directory structure for libraries"

This reverts commit 7490029866c2e4676c0be21670e51d9f89bbaea8.
started writing tests for current implementation + bugfixes
added mailing list link to readme
skeleton for message deserialization finished, merged dart coin.wire into dartcoin.core

This was required because message classes use library private  methods from BitcoinSerialization.